Footnotes

• Handling editor Ellen J Weber

• Contributors T-NL wrote the manuscript and prepared the images. C-HC revised the manuscript and prepared the images. S-CC obtained patient consent and wrote the manuscript.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting or dissemination plans of this research.

• Provenance and peer review Not commissioned; internally peer reviewed.